This invention relates to an improved apparatus for dispensing wound material. More particularly, this invention relates to an apparatus for dispensing material on a feed spool to a take-up spool by rotating the feed spool in the direction opposite to the direction in which the material is wound.
The basic concept of an apparatus for transferring wound material from a feed spool to a take-up spool is to act in cooperation with a machine which will operably engage the material during the time the material passes between the two spools. In the case of a ribbon cassette, the ribbon may be contacted by a printing device of a typewriter, a word processor, a computer printer, and the like.
A threshold or common denominator of almost all devices for transferring wound material between feed and take-up spools is a smooth and orderly transfer of the material. A common problem encountered in such devices is the occurance of material jamming along the path between the spools which causes a temporary or permanent delay in a transfer procedure. For instance, an operator of a typewriter or word processor, after inserting a ribbon cassette into a machine, may be unable to properly operate the machine because of jamming of the ribbon cassette. In such event, the operator must remove the cassette from the machine and either attempt to resolve the jam, often by sacrificing some length of fresh ribbon, or dispose of the cassette with fresh ribbon remaining on the feed spool. Such a procedure is troublesome both in terms of the time spent in correcting the problem and in the cost of the cassette itself.
Over the years the business machines industry has attempted to reduce jamming in ribbon cassettes and other such devices in order to improve product performance and reliability. The proper amount of ribbon feed is generally dictated by drive gears on a take-up side of the cassette. Jamming frequently occurs at a printing area when the ribbon unwinds from the feed spool at a rate which is faster than the rate at which the ribbon is wound upon the take-up spool. To correct this problem, many cassettes and other such devices now include frictional drag means which are positioned against the rotating feed spool in order to prevent pulling an excess amount of ribbon from the supply side of the cassette.
Devices attempting to produce a frictional drag on the feed spool have included such drag means as foamy material, o-rings, and springs which apply force directly to the ribbon itself. However, serious advantages are associated with these means. Foam is inconsistent because it is directly effected by the width of the material on the feed spool, and o-rings can be adversely affected by heat degradation. Springs which act directly on the ribbon itself apply a force which changes drastically as the ribbon diameter decreases. The ribbon may also suffer contamination from oily sustances on the spring which may not be removed by the manufacturer.
While such systems, as previously noted, have received at least a degree of industry recognition, room for significant improvement remains. In this regard, the absence of any preventative means increases the frequency of material jamming and results in loss of operator time and money. However, the above-mentioned means for producing a frictional drag on the feed spool also includes serious disadvantages such as inconsistency of drag, heat sensitivity and contamination of the ribbon.
The problems suggested in the proceeding are not intended to be exhaustive, but rather are among many which may tend to reduce the effectiveness of prior devices for transferring material between a feed spool and a take-up spool.
Other noteworthy problems may also exist; however those presented above should be sufficient to demonstrate that devices which transfer material between a feed spool and a take-up spool have not been altogether satisfactory.